Telephone system



Dec. 3, .1929. A. KRECEK I1,738,302

TELEPHONE SYSTEM t/Usey A. /f/ece/f.

Dec. 3, 1929. J. A. kREcEK 1,738,302

TELEPHONE SYSTEM Filed Aug. 28, 1926 '7 Sheets-Sheet 2 Dec. 3, 1929. J.A. KRECEK 1,738,302

TELEPHONE SYSTEM Filed Aug. 28, 1926 7 Sheets-Sheet 3 llll mgm.

//7|/e/7/0/f Josep/7A. ece/r.

Dec. 3, 1929. J. A. KREcl-:K 1,738,302

TELEPHONE SYSTEM Filed Aug. 28, 1926 'T Sheets-Sheet 4 '7 Sheets-Sheet 6IPH Dec. 3, 1929.

J. A. KR'ECEK TELEPHONE SYSTEM Filed Aug. 28, 1926 '7 Sheets-Sheet '7056% @Ce 714/ ,4f/y

Patented Dec. 3, 1929 N UgNiTsn STATES PATENT OFFICE JOSEPH .A. KRECEK,OF BROOKLYN, NEW YORK, ASSIGNOR T0 BELL TELEPHONE LABORATORIES,INCORPORATED, 0F `NEW YORK, N. Y., A CORPORATION OF NEW YORK Applicationfiled August 28, 1926. Serial No. 132,105.

This invention relates to telephone eX- change` switching systems, andmore particularly to the automatic selection of speech amplifying andrepeating apparatus and the insertion ot the same in toll connections.

l-lferetoi-ore systems such as those disclosed in the Patentl`lo.\1,6417,796, issued to L. L. Glezen, S. P. Shackleton and E. Vroon,November 1, 1927, and the application of E. Vroom and F. S. Entz, SerialNo. 129,682, tiled Aug. 17, 1926, have been designed -'or the selectionof repeaters and the inclusion oi the same in toll lines. In, generalthe arrangements in these systems are such that the automatic actionsare started on the interconnection of two linesby` means ot a cordcircuit. An idle repeater is first selected and then connected betweenthe two lines by means of various kinds ot switching apparatus.

The present invention is embodied in an arrangement in which one end otan automatically selected repeater is connected, by means or' anindividual line linder, with the call originating line, while a trunkfinder individual to the called line operates to select the other end ofthe repeater, thereby effecting an interconnection of an idle repeaterbetween these two lines.

Furthermore the present invention contemplates a grouping ot the tolllines and repeaters such that the repeaters of any group serve, not onlyfor toll connections involving two lines in their own group, but forconnections involving one line in their own group and another line inany other group.

ln large exchanges, tollline tra'liic may be conveniently arranged so`that certain groups of lines will always be answered by certain groupsof cords. Taking advantage `oi `this arrangement, the system of groupingin accordance with this invention is such that each group of cords willhave a definite group of repeaters assigned to it. Each repeater isconnected at its incoming end with a line finder having direct access toall theV lines in the group that may be answered by cords having accessto the `corresponding group of repeaters. `On the other hand, theoutgoing end of each repeater in each group may be reached by having thelines in each group individually terminating in a trunk inder havingaccess to a plurality of trunks that are common to the trunk finders foreach group of lines. Each of these trunks terminates in a repeaterfinder having access to all or' the repeaters of all groups.

It should be understood that the expression cincoming or outgoing end ofa repeater is merely used for convenience in distinguishing between thetwo ends of repeaters from which connections are made to lines or towhich connections are made trom lines and does `not roter to thetransmission character- Fig. 2 shows an incoming line and its as-`sociated trunk linder.`

Fig. 3 shows a repeater finder in which a trunk from the trunk findershown in Fig. 2

terminates and a line finder having access to the incoming line shown inF ig. 2.

Figs. 4 and 5 illustrate a cord circuit ofthe group serving the group oflines of which the line shown in Fig. 2 is one and the associatedrepeater selector and a repeater,the repeater being merelyy indicated bymeans of an enclosure. These two iigures also show various commoncircuits and switching arrangements tor preventing more than oneinterconnection ot toll lines from taking place at any one time, thiscommon equipnfient being similar to the equipments for the same purposeshown in the above mentioned copending applications.

6 illustrates the incoming end of another line .requiring the additionof a repeater and the associated trunk selector, while Fig. 7illustrates a repeater finder as- 40 u tween'two'linesin these groups toinclude a I sociated with a trunk from the trunk finder shown in Fig. 6,and a line finder` having access to the group of lines over which theline shown Ain Fig. 6 is one.

Fig. 8 shows lthe arrangement of the various-drawings forming part ofthis applical be divided into groups two of which 1 and 2 of one`hundred lines each have been indicated. Each of these groups of linesmay be answered by a group ofcords, the group 3 being used for answeringcalls incoming over lines in groupV l and the group 4 being yused forcallsincoming over the linesof group 2. The cor-ds in A'group 3 yareeach provided with av repeater selector,such as 5 and 6 having v"accessto repeaters, such as'7 and 8, of a group of approximately twentyrepeaters. The incoming ends of these repeaters terminate inlinefinders, such as 9.and 10 having access'to all of the lines in group 1.The cord circuits of group 4 are each provided with a repeater selector,suchas 12 and 13 havingaccess toprepeaters, such as 14 and 15 of agroupof approximately twenty repeaters. The incoming ends of theserepeat- ,"e'is are connected to line finders, such as 16 and17"`1havingaccess tov all of the lines in group 2. ,y Each of the lines in groups 1and 2 is provided with a trunk finder, such as 20,

in21, l22` and 23. Each of these trunk finders -'ha-s'access toapproximately twenty trunks terminating in repeater finders, such as 25,26,127 and28, all'of which have access to the outgoing ends of'all ofVtheforty repeaters in thetwo groups shown. A .connection berepeater,may bel established by inserting for example ithe left-hand end ofa'vplug from a cord in group 3 into a ack of a line of group 'l andinserting the right-hand plug of said cord into a jack of a line ofeither group 1 .orgroup 2 depending on where the wanted line is located.The connection of two lines in this manner ywill. cause an idle repeaterto be Iselected by a repeater selector, such as 5 or 6, rVhen thisselectionV has taken place a line finder, such as 9 or 10, associatedwith the incoming end of the selected repeater finds the calling lineand connects it to the selected repeater. A trunk finder of a wantedline 'their selects an idle trunk and the repeater finderV connected tothe selected idle trunk the outgoing end of the selected repeater.Aconnectioniwill now be established, for example,y as follows: From aline in group 1 through a line finder, such as 9, a repeater,

such. as 7, a repeater finder, such as 25, a trunk "finder,l such as 20,and the associated line in grou 1 or from the repeater 7 through arepeater, nder, such as 27, a trunk finder,

such as 22, and the associated line in group 2. lVlien this connectionis completed the talking conductors of the cord circuit employed areopened and a talking connection through the repeater is established.

Referring now to Figs- 2 to the-general scheme of.l interconnecting tolllines and inserting repeaters into these connections in accordance withthis invention will be .outlined as follows :"Letit be assumed that thetoll line A is to be connected through anrepeater with the toll line Band that cord circuit C is to be used for the establishing of thisconnection. In accordance with wellknown practice, a call incominof overline A causes a lam such as 200, to l.be lighted at the toll boar s. Anoperator having charge of cord circuits, such 'as C, in answering thiscall inserts plug 400 into jack 201 and operates the talking key 401 toconnect her telephone set to line A for the purposeof communicating withthe operator 'at the distant end to ascertain the destination of'thedesired connection. After having received the desired information, theoperator inserts plug 403 intojack 600 of line B and restores thetalking key 401.

As both lines A and B'require the inclusion of a repeater, these lineshave special electrical characteristics in their sleeve circuits thatwill initiate, whcn the toll lines are connected to the cord circuit,automatic operations for the insertion of the repeater inthe connection.For this purpose, there is provided a so-called lockout selector switchor cord finder, one of which is indicated at D. Each cord finder iscommon to a group of cords. The cord finder D will now start to find thecord C and when found, the cord finder remains associated `with the corduntil the operations for inserting the repeater in the connection arecompleted. This is in order to prevent any other ycord circuit in thisgroup from starting its operations until cord C is released. `As soon ascord finder D finds the cord circuit C, operations are started toactuate lthe secondary lockout circuit or position finder indicated atE. This finder is common to all groups of cords in the system. Theposition finder E remains associated with the cord circuit C until thecomplete sequence ofoperations for the insertion of the repeater intothe connection has been effected and functions to prevent any other cordcircuit in any other group from starting theselection of a repeateruntil the cord circuit C has completed its functions in this respect.The actuation of the position finder takes place immediately, providedno other cord in the system is going through the'process of inserting arepeater in a connection. The reason for the provision of a cord finderfor each group of cords and aposition' finder for all the groups ofcords in the system is to insure thatlonly one connection-of a repeaterbetween two toll lines may take place at any one time. In order howevernot to delay the connection ot repeaters any longer than is necessary,the cord finders oi the ditferent groups ot cords may operate to iindcords interconnecting toll lines independently and simultaneously andprepare the associated circuits to the point where the common positioniinder begins to operate to permit one cord circuit at a time tocomplete the repeater selecting and connecting tunctions.

@nce the cord circuit C has assumed control over the position iinder E,it starts its repeater selector indicated at F to huntior repeater. Unerepeater' has been indicated at Gr merely by means of an enclosure withall the leads from the line finder connected to the incoming end ot therepeater and with all the leads trom the repeater linders having accessto the outgoing end ot the repeater and all the leads from the repeaterselector F shown leading into this enclosure. As the repeater itselfforms no part of the invention and as any repeater oi.l any well-l-.nowntype may be used, it is thought that this representation will besuilicient. The repeater selectors and cord iinder switching units maybe ot any well-known type having a series ot' terminal banks with thebrushes arranged to travel thereover in steps under the control oitstepping mechanisms. These selectors and iinders have no home positions.

l'lvlhen the repeater selector F finds an idle iter, certain electricalconditions are esshed i'or the sleeve circuits of lines A and ll tocause these lines to be connected together through the selectedrepeater. First,4 the line ri is connected through the line l'inder "ilto the incoming end oi'repcater G and then line B is connected throughthe trunlf; Ender l and a repeater finder, such as lil. to the outgoingend oi repeater G. In addition to line finder H tor linding line A,there has also been shown a line finder L individual to this line A anda repeater finder lil, the brushes ot which are connected through atrunlr terminating in the banks of the line linder la. This repeaterfinder having access to the outgoingl ends of all of the repeaters inthe various groups, it should be note? that a similar showing has beenmade 'for line B, that is, a line finder N from the incoming end ot arepeater has been shown. This line finder has access to the group inwhich the line B .is located. This showing has been made in order toclearly bring out the tact that these lines can be reached throughswitches, such as H or N, and may iind the outgoing ends oll repeatersthrough such switches as L and M or l. and lli. The construction ci thetrunk finders L and l may be oi any well-lrnown type having a series otterminal banlrs with brushes arranged to travel thereover in steps undercontrol of stepping magnet mechanisms. These selectors have no homepositions. The construction ot the repeater finders M and K and lineiinders H and N may be of any well-known Strowger type, having terminalbanks arranged in horizontal layers with brushes traveling in a verticalfollowed by a horizontal step-by-step movement.

As soon as the lines have been connected with the repeater, the cordfinder and the position finder are released so that the cord linderbecomes available :tor other cords in the group to which the cord Cbelongs and so that the position iinder becomes available for this orany other group of cords. Cin cuit changes will now take place toseparate the two lines from the cord C and connect them to the repeaterin the manner above mentioned, and at the same time, connect thenetworks N1 and N2 to balance the lines and also to remove certain shortcircuits in the selected repeater to make it operative. Transmission maythen take place through the repeater while the connection through thecord circuit is opened. i

Arrangements are also made whereby when the talking lrey of the cordcircuit is operated, the repeater is cut out from the connection, whichunder these circumstances will extend through the cord circuit.Monitoring lreys are also provided whereby connections from the repeaterto the operators telephone may be established through therepeaterselector.

It either one ofthe plugs of cord C is witlidrawn from the line jack,the repeater is released from the connection. The repeater selectorbrushes, the cord iinder brushes, and the trunk linder brushes willremain in the position in which theywere last used, while the line inderand repeater finder are returned to normal position. The sleeve circuitot the line still connected to the cord remains in busy condition untilboth plugs are removed, when the entire equipment is re stored to normalcondition.

For the purpose of providing for failure ol any part oi'l the systemduring the establishing oit a connection involving a repeater, the timealarm circuit indicated by T is used. Each connection is allowed acertain time, tor example, ve seconds in which to be completed. Itcompleted within this tmc, the time alarm circuit is restored to normal,but it it is not completed in the allotted time, the time alarm circuitfunctions to give an alarm indicating which cord circuit is involved andalso to cause the release of the cord finder involved to allowconnections through another cord to take place. Cord circuits, such asC, are also arranged for interconnecting ordinary toll lines that donotl require addition of repeaters. However, the invention isessentially concerned with the inclusion ot repeat ers in toll lineconnections and the following ycuitfor the lighting of lamp 200. Theoperator at C answers this call by inserting the plug 400 into jack 201and by connecting her 210 and 402'.

telephone set through cord C to line A for the purpose of communicatingwith the operator at the distant end of the line A to ascertain`thedestination of the desired connection. The vfirst effect after theinsertion of plug V400 into jack 201 and before key 401 is operated willbe the. extinguishing of lamp 200.Y Afcircuit is completed through 4the'sleeve terminals of jack 201 and plug 400 as follows: Battery, Windingof relay 402, righthand winding of relay 404, left-hand armatureand backContact of relay 405, sleeve terminals of plug 400 and `jack 201,left-hand winding of marginalrelay 210 to ground. This circuit causesthe operation ofrelays Thek `operation of relay 210 ycloses an obviouscircuit for the relay 211, whichV in turn, closes an obvious circuit forrelay 212. The operation of relay 212 opens the original energizingcircuit for relay 210 Yand closes at its left-hand armature and frontcontact a'connection from the sleeve `through ythe right-hand windingsof relays 211 and :210 in series jto ground, thus holding these tworelays operated. The operation ofrelay 212 also closes an obviouscircuit for the operation ofv relay 207, which in operating, opensy theholding circuit for relay 206 and 'also the circuit for relay 205. Relay206 in f releasing causes the lamp200 to be extinguis'hed.

When relay 402 operatesa circuit is closed for the operation `of relayV406 as follows: Battery, winding of relay 406, right-hand armature andback contact of relay 404, lefthandV armature and front contact of relay402 to ground. Relay 406 provides a locking-,circuit for itself`directly through its left-hand armaturer and front contact to theground at the left-handarmature and front contact of relay 402,independent of the original .energizing circuitthrough the armature andback Contact of relay 404. Relay'404` being marginal does not operate aslong as the sleeve circuit extends through the left-hand winding ofmarginal relay 210. As

soon as the sleeve circuit is changed to extend` through the right-handwindings of relays 211, andt2l0A in. series, 1 the resistance of the 1.

circuit is changed, as the resistance of the right-hand windings ofrelays 211 and 210 is low as compared with the resistance of theleft-hand winding of relay 210. Hence, when relay 212 operates, thischange in the resistance of thel sleeve circuit causes relay 404 tooperatefto open the original energizing cirlcuit for relay 406. Theoperation of relay 402 closes a circuit for the operation of relay 407as follows: Battery, winding of relay 407, armature and back Contact ofrelay 408, left-hand make-before-break contact of relay 410, right-handarmature and front contact of relay 402 to ground. It should be notedthat this circuit extends through armature and back contact of relay 407to the winding of relay 412 and battery, but as relay 412 is slow inoperating as compared with relay 407, it Will not have time to operatebefore the circuit for this relay is broken by the operation of relay407. The non-operation of relay 412 prevents relay 413 from operatingand consequently prevents the lighting of lamps 415.

The operator will now actuate the talking key 401 to associate hertelephone set with cord circuit C. After ascertaining from the operatorat the distant end of toll line A the destination of the desiredconnection, the operator will now insert the plug 403 into jack 600 ofline B. rlhe eiiect of this connection is similar to the eifect ofinserting plug 400 into j ack 201. That is, a circuit is completed frombattery, winding of relays 418, 420 and 421 in series, armature and backcontact of relay 422, sleeve terminals of plug 403 and jack 600,makebefore-break contacts of relay 612, right-hand winding of marginalrelay 610 to ground. The immediate eli'ect of this circuit will be tocause the operation of relays 420 and 610. The operation of relay 420causes an obvious circuit to be closed for the operation of relay 423,which relav, in operating, closes a locking circuit for itself throughits rifrht-hand armature and front contact directly to the ground at therighthand armature and front contact of relay 420. The operation ofrelay 610 closes an obvious circuit for the operation of relay 611, andrelay 611, in operating, closes an obvious circuit for the operation ofrelay 612. Relay 612, in operating, opens at its make-beforebrealicontacts the circuit through the righthand winding of relay (310 andextends the sleeve circuit, through the right-hand armature and frontcontact of relay 612, through the left-hand windings of relays 611 and610 in series to ground. The resistance of the circuit through thesewindings is low as compared with the resistance of the right-handwinding of relay 610, so that on the operation of relay 612, theresistance characteristics of the sleeve circuit change to cause therelays 418 and 421 to operate. The operation of relay'421 causes theoriginal energizing circuit for relay 423 to be opened and the operationof relay 418 closes an obvious circuit for the operation of relay 425 totransfer the relay 426 to a diiferent bridge circuit across the talkingconductors of the cord circuit C for establishing conditions relating tothe supervision of the connection as will hereinafter become apparent.The operation of relay 420 also closes an obvious circuit fortheoperation of relay 428, which relay in operating closes a lockingcircuit for itself through the inner left-hand armature and frontcontact of relay 423, outer right-hand armature and back contact ofrelay 429, inner right-hand armature and front contact of relay 406 toground. Relay 423 closes through the tip conductor to the tip terminalsof plug 403 and jack 600 of cord circuit C.

The cord finder D will now be actuated to lind the cord C. The terminalof cord circuit C on bank 501 will be marked by the absence of batteryas it will be seen that the operation of relays 406 and 423 removesbattery connections to this terminal. The starting magnet 500 for cordlinder D will also start to operate the brushes of the cord finder Dover a circuitas follows; Battery, from relays corresponding to relays406, 410 and 423 of idle or busy cords, through the corresponding`terminals and brush of bank 501, winding of stepping magnet 500, throughits armature and back contact, through the left-hand armature and backcontact of relay 503 of the position finder E, righthand armature andhack contact of relay 431, inner left-hand armature and front contact ofrelay 423, outer right-hand armature and back contact of relay 429,inner righthand armature and front contact of relay 406 to ground. Asthe stepping magnet 500 breaks its own circuit, it will continue tooperate until the terminal of the bank 501 from which battery has beenremoved is found. This terminal is associated, as stated, with the cordcircuit C and when the stepping magnet stops its operation, relay 502will operate. Relay 502 has a high resistance winding and operates inseries with the stepping magnet without causing the stepping magnet tooperate.

Relay 502, in operating, locks through a resistance 505 and itsleft-hand armature and front contact to ground and remains in thiscondition until it is released, as will hereinafter be described. Theoperation of relay 502 closes a circuit for the operation of relay 510as follows: Battery, through the inner left-hand armatures and backcontacts of relays corresponding to relay 503 that are individual toother groups of cords in the position finder E, through the winding ofrelay 510, right-hand armature and front contact of relay 502 to ground.Relays 510 and 503 of the position finder are individual to the group ofcord circuits of which cord C is one. The individual relays, for eachgroup of cord circuits, corresponding to relays 510 and 503 areconnected in a manner similar to these relays. Two sets of such relaysis shown to the left of the two relays individual to this group of cordcircuits. On the operation of relay 510 an obvious circuit is closed forrelay 503 which by operating its lefthand armature opens the connectionfor the stepping magnet 500. Thus no other cord in this group can causecord iinder D to operate until the release of cord circuit C in themanner to be hereinafter described. Similarly, the operation of relay510 by attracting its armature removes ground normally connected in achain circuit through the armatures of other relays corresponding torelay 510 in other groups so that none of the relays corresponding torelay 503 can be operated while relay 510 is actuated. Connections fromcord circuits in. other groups are therefore prevented from goingthrough the position finder until the functions of the cord circuit Care completed.

0n the operation of relay 503 a circuit is closed for relay 512 asfollows: Battery, winding of relay 512, inner right-hand armature andfront contact of relay 503, righthand armature and front contact ofrelay 502 to ground. The operation of relay 503 closes a circuit tobattery through bank 513, through the cord circuit C to cause theoperation of the repeater finder F. This circuit inaybe traced asfollows: Battery, inner left-hand armature and back contact of relay514, outer right-hand armature and front contact of relay 503, windingof relay 515, brush and a selected terminal of bank 513, winding andarmature and back contact of stepping magnet 516 of the repeater finderF, left-hand armature and back contact of relay 431 to the brush of bank519 of the repeater finder F. If the brushes of the repeater finderhappen to rest on the terminals of a busy repeater, which is indicatedby the fact that a ground is connected to a corresponding terminal ofbank 519, the stepping magnet 516 will start to operate and advance thebrushes of repeater finder F until an idle repeater is found which isindicated by the absence of ground on the correspondingterminal of bank519, or as in this case, the presence of battery on this terminal. Inother words, if a busy repeater is encountered, ground will be connectedthrough brush 519 to a corresponding multiple contact of the repeaterfinder connected to the busy repeater. This ground will be supplied fromthe left-hand armature and front Contact of the relay corresponding torelay 431 in the engaged cord circuits. lt will be noted that a circuitis established for relay 431 at the same time that a circuit isestablished for relay 515. The circuit for relay 431 may be traced asand'back contact of relay 514, outer right-- hand armature and frontVContact of Vrelay 503, outerlet-hand armature and front contact ofrelay 512,- armature and back contact of Vrelay 515, to brush andcorresponding terminal of banlr 520, left-hand winding 'of relay 531v toground. Relay 515 in the above mentioned circuit is a fast operatingrelay as compared to relay 431 which is slow to operate. The operationof relay 515 will thereforeY prevent relay 431 from operating atthis/time although a circuit for relay 431 is completed through thearmature and back contact of relay 515. The

stepping-magnet 516 will continue to operate until an idle repeater isfound, that is, one that has no ground on its multiple terminal of thebank 519. This circuit through the relay '515 andthe stepping magnet 516willtherefore be opened, that is, when no ground is found on thecorresponding ter- `Ininal of bank 519 the release of relay 515 and thestopping ot magnet 516 takes place, so that thebrushes of the repeaterfinder F `:v'villnow rest on the terminals of the first idle repeater.When this takes place, the previously traced circuit for relay 431 willfbe Ycompleted throughthe armature and back contact of relay 515 so thatrelay 431 vwill-now `be energized and apply ground to its' left-handarmature and front contact Dthrough'the brush 519, thus making therepeater G busy to other cord circuits.

l Relay 431, in operating, provides a locking circuit tor itself throughits right-hand Varmature'andiifront contact, left inner contactv andarmature "of relay 423, right outer normal contact and armature of relay429, to the ground at the inner right-hand armature and front contact ofrelay 406. The operation of relay 431 also closes a circuit for thevoperation of relay 405 as Jfollows: Battery,fwinding oi relay 405,right-hand armature and front contact of relay 431 to 'the'ground attheinner right-hand armature A,and front contact of relay/406. Theopera- 'tion of relay 405 byopening the connection through `its lefthandarmature and back Contact forthe sleeve circuit for plug` 400 andjaclr201 causes a resistance 432 to be inserteclin the'sleeve circuit. Theeti'ect of the insertion of this resistance is that the marginal relay210 will be released. Relay 210 Ain releasing closes a circuit for theoperation of relay 215 as follows: Battery, winding of relay 215,right-hand armature and back contactof relay 210, armature and frontcontact 'of relay 211 to ground. The operation ot relayf215 closesaconnection to ground at its innerleft-handarmature and front contact ofline finder H -is operated over a circuit as follows: Battery, windingof relay 300, a terminal and the brush of banlr 519, letthand armatureand front contact ot relay 431 to ground. The operation of this relayand relay 215 above mentioned will therefore close a circuit for theoperation ot relay 217 as follows Battery, outer lett-hand armature andfront Contact et relay 300, outer leftiand armature and back contact ofrelay 518, middle left-hand armature and front contact o'l' relay 215,outer right-hand armature and back contact ci relay 218, lett-handwinding of relay 217, make-beiore-break contacts oi this relay,make-betorc-break contacts ot relay 218, inner left-hand armature andfront contact of relay 215 to ground. The opera` tion oit relay 217opens the circuit from ground at the inner left-hand armature andTt'ront Contact ot relay 215 through the makebetore-brealr contacts oi'relay 217 and extends this circuit through the inner righthand armatureand Jiront contact and the right-hand winding of relay 217 to battery tolock relay 217 under the control of relay 215. While a circuit ispartially completed for relay 218 on the operation oit relay 215 thisrelay 218 will not operate due to the fact that line A is the calloriginating line. It will bc expiained in the description relating tothe association of lines B with the outgoing end ot the repeater G how arelay corresponding to relay 218, namely relay (518, in the circuit forline B will be operated, while a relay 617 in this circuit correspondingto relay 217 in. the circuit tor line A will not be operated due to thetact that line B is the wanted line. Thus, by the operation andnon-operation of these relays, discrimination between an incoming lineand an outgoing line is determined. rlhe operation of relay 217 closes acircuit for relay 220 as follows: Battery, winding of relay 220,left-hand armature and back Contact ot relay 221, outer left-handarmature and iront contact ot relay 217 to ground. Relay 220 is commonto all of the lines of the group of which line A is one that terminatein the same level of line inder H as line A. The operation of relay 220by closing its armature and front contact to battery will mark the levelof line iinder H in which line A is located.

Upon the operation of relay 300 an obvious circuit is closed for theoperation of relay 301. rlhe operation ot relay 301 closes the circuit'tor the operation et relay 303 as tollows: Battery, winding` ot relay303, armature and back contacts of vertical magnet 305 and rotary magnet300, right-hand armature and front contact of relay 301, armature andbach Contact of relay 307, rigli`l1and armature and 'front contactofrelay 300 to ground. The operation of relay 303 closes a circuit for theoperation of the vertical magnet 305 as follows: Battery,

armature and front contact of relay 303, lefthand armature and hackcontact ot relay 3011, Winding et Vertical magnet 805, armature andleach contactot relay 307 and righthand armature and liront Contact ofrelay 300 to ground. As the vertical magnet 305 operates the circuit forrelay 303 is opened. The release et relay 303 opens the circuit for thevertical magnet which in releasing again closes the circuit for relay303 to reoperate the Vertical magnet 305. Thus the alternate operationand release of vertical magnet 305 causes the brushes of switch l-l totravel in a vertical direction until the brush 310 linds the terminal311 Which marks by a battery from relay 220 the level in which theterminals oit line A are located. A circuit will noW be completed fromthe battery at the armature and iront contact ot relay 220, terminal311, brush 310, left-hand Winding ol relay 304i, inner lett-handarmature and iront conA tact of relay 300, armatrn'e and haelt Contactof relay 307 to ground at the right-hand armature and front contact ot'relay 300.

The operation ot relay 30a opens the circuitcuit tor the Vertical magnet305 which now ceases its operations and the circuit from battery at thearmature and front contact of relay 303 is transferred to close thecircuit tor the rotary magnet 306 as follows: Battery, armature andfront contact of relay 303, letthand armature and front contact ot'relay 304:, Winding of rotary magnet 306, armature and hack contact etrelay 307, right-hand armature and front contact ot rel ay 300 toground; rllhe alternate operation and release of rotary magnet 306 andrelay 303 take place in the same manner as during the operations of thevertical magnet 305. It Will loe noted that when the terminal 312 oitline A is reached hy the brush 314 ot finder H, battery Will loesupplied from the inner left-hand armature and front contact et relay21',7 'lor the operaion or relay 307 over a circuit as follows: Battery,inner lett-hand armature and front contact of relay 217, Winding ofrelay 221, terminal 312, brush 314, right-hand Winding of relay 307 andupper vertical oil normal contacts 315 to ground. rlhis circuit causesthe operation et relays 221 and 307. The operation oit relay 307 opensthe energizing circuit for rotary magnet 300 and relay 303 causing thebrushes ot iinder H to stop on the terminals of line A. Relay 307 islocked up to the ground at the right-hand armature and front contact ofrelay 300 over the armature and front Contact ot relay 307. Theoperation of relay 307 also closes a circuit tor the operation of relay308 as :fellows: Battery, Winding of relay 308, armature and trentcontact et relay 30? to ground at the right-hand armature and irontcontact of relay 300. The operation et relay 308 closes the connectionbetween the conductors from line A through to the incoming end ofrepeater Gr. A circuit ture and front contact et relay 221, lett-handarmature and haelt contact of relay 226, upper Winding of relay 224 toground. rlhe operation or' relay 224 applies ringing current from source228 to the conductors of line A leading te the incoming end of therepeater G through the armatures and trout contacts ot this relay andthe armatures and iront contacts ot relay .229. It should he noted thatrelay 220 Was operated upon the operation oi' relay 217 over a circuitas follows: Battery, Winding of relay 229, inner rightehand armature andfront contact ot relay 217, inake-beiore-hrealr con tact et relay 218,inner lett-hand armature and trent contact of relay 215 to ground. Thepurpose oi applying ringing current to the conductors troni line A tothe incoming end of repeater G is to burn out the terminals and hrushconnections between the line finder H and the conductors oit line A.

Relay 518 in operating closes a circuit for the operation of relay 122as follows: Battery, inner righthand armature andlront Contact ot relay518, brush and a terminal ot haul; 582, middle right-hand armature andtrent contact el' relay 405, Winding of relay L122 to ground. Relay 1-22in operating @langes the resistance characteristics of the sleevecircuit Yfor plug` 403 and ack 600 which causes the marginal relay @l0to release. The release ot relay 610 causes a circuit to he closed 'forthe operation of relay 615 as follows: Battery, winding of relay G15,lefthand armature and haelt contact o1 relay 610, armature and trentcontact ol relay 611 to ground. The operation of relay 615 closes acircuit for the operation of relay 018 as tollows: Battery, outerright-hand armature and front contact ot relay 01.8, outer lett-handarmature and back contact oi relay 514, outer right-hand armature andtrent contact ot re lay 615, rightehand winding ot relay 618, outerlett-hand armature and hack contact and inalre-hetore-hrealr contacts otrelay 617, malte-hefore-break Contact of relay 618, inner right-handarmature and front Contact oit re lay G15 to groundy Relay 61S inoperating closes a locking circuit for itself through its lett-handWinding and inner lett-hand armature and liront contact to the ground atthe' .inner right-hand armature and trent contact of relayll. A circuitmay new he Closed by the operation oit relay 618 for the operation etthe stepping" magnet 631 in series with the relay 032 lor the operationof the trunk selector l.

Vll)

Ifl the brushes of this selector are resting on lterminals'vof'a busytrunk the stepping magnet 631 will operate and a circuit will be closedfor this magnet and the relay 632 as -follows: From battery, innerright-hand armature and front contact of relay 618, winding, armatureand back contact of steppingmagnet 631, winding ot relay 632, righthandarmature and back contact of relay 633 brush o'fbank 640 of switch I tothe terminal ofthe busy trunk at this bank and a corresponding brushv ofa busy trunk selector such as I, to ground at the right-hand armatureand front contact of a relay of the busyjline corresponding to relay 633ot this line. .It will be noted-that a circuit is also closed'by theoperation of relay 618 for relay 633 from battery through the winding ofrey Y lay 633 through the armature and back contact of relay 632 toground at the outer righthand armature and front Contact 0f relay 618.But as relay 632 is faster in operating than relay 633 the circuit forthis latter relay will be opened as long as relay 632 is operated andstepping magnet 631 is alternately operated to advance the brushes ofswitch I until they come in contact with the terminals of an idle trunk.At this time the brush of bank 640 encounters battery on thecorresponding terminal and consequently relay 632 and magnet 631 will bereleased. lVhen this takes place the above mentioned circuit for relay633 is completed and this reay will. now operate to apply at itsright-hand armature and front contact a ground to make t-he selectedtrunk busy to other trunk finders such as I. The release of relay 632closes a circuit for the operation of relay 624 over a circuit asfollows: Battery, lower winding of relay 624, left-hand armature andback contact of relay 626, armature and back contact of relay 632 'toground at the outer right-hand armature and front contact of relay 618.Relay-624 in operating applies ringing current'from source 628 to theconductors of line B leading through switch I the selected brush andswitch K to the outgoing end of the repeater jack to burn out thecontacts of these switches as is well known in the art.

It should be understood, however, that the vresponding terminal and thebrush of bank 640 of switch I, left-hand armature and frontcontactofrelay 633 to ground. The operation of relay 700 closes acircuit i'or the operation of relay 703 as follows: Battery winding ofrelayl 703 armatures and back contacts of vertical magnet 705 and rotarymagnet 706,

armature and back contact of relay 7 07, lefthand armature and frontcontact of relay 700 to ground. The operation ot relay 703 provides, bythe operation of its armature, battery for the operation of the verticalmagnet 705 as follows: Battery, armature and il'ront contact oit' relay703, right-hand armature and back contact ot relay 704, winding ofvertical magnet 7 05, right-hand armature and front contact of relay700, armature and back contact ot relay 707, lett-hand armature andfront contact of relay 700 to ground. The operation 01' vertical magnet705opens the circuit for relay 703 which in releasing opens the circuitfor the vertical magnet 7 05. Thus this relay 703 and vertical magnet705 will alternately operate and release to advance the brushes ofrepeater finder K to tl e horizontal level in which the terminals of theoutgoing end oi' repeater G are located. It will be noted that thislevel is marked by a battery applied from the armature and front contactof relay 525 to terminal 711. Hence, when the brush 710 finds thisterminal a circuit is closed for the operation ot relay 704 as follows:Battery, armature and ilront contact of relay 525, terminal 711, brush710, right-hand winding of relay 704, armature and back Contact of relay707, left-hand armature and front contact of relay 700 to ground. Relay704 in operating transfers the battery at the armature and front contactof relay 703 from the vertical magnet to the rotary magnet.

The circuit tor the rotary magnet may be traced from this battery,right-hand armature and front contact of relay 704, winding ot rotarymagnet 706, ri glit-hand armature and front contact of relay 700,armature and back contact of relay 707, lefthand armature and frontcontact of relay 700 to ground. Relay 703 and rotary magnet 706 will nowalternately operate and release until the brushes ot repeater iinder Klind the outgoing terminals of repeater Gr. It will be noted thatterminal 712 has been marked by a battery on the operation of relay 518so that when brush 714 finds this terminal a. circuit is completed forthe operation of relays 707 and 514 as follows: Battery, middleright-hand armature and front contact of relay 518, winding of relay514, terminal 712, brush 714, lcft-hand winding of relay 707, verticaloli' normal contacts 715 to ground. Relay 7 07 in operating opens thecircuit for the rotary magnet 706 at its armature and back contact andcloses through its armature and the corresponding front contact alocking circuit for itself to the ground at the left-liand armature andfront Contact ot relay 7 00. A circuit is also completed by theoperation of relay 707 for the operation. o1 relay 718 which joins theselected trunk conductors to the brushes of repeater finder K. At thistime the ringing current 'from source 628 is passed through the brushesand terminals of switches I and K to burn them out.

Relay 514 in operating opens at its outer left-hand armature and backcontact the "original energizing circuit for relay 618 Which,however,,remains operated as hereinbefore described. This relay alsoopens a circuit for relay 525 Which releases to remove the markingbattery from the terminal 711. 1o

lt might be explained here that if during the vertical movements of theline finders H or K the marking of the terminals such as 311 or 711should for some reason not be 'identified by the brushes 310 and 710,the vertical magnets 305 or 705 Would continue to step the brushes upuntil the 10th levelis reached which time relays 304 or 704 Wouldoperate from `the battery supplied at the 10th level through brushes 310or 710. ln this case the rotary magnets 300 or 706 Would opc'ate tostepthe brusnes over the 10th leveluntil the 11th rotary step is reached forthe operation of the 11th step rotary contacts or 7 28. `The operationof these contacts would cause the operation of release magnets 322 or722 over obvious circuits so that these switches would be restored totheir normal positions. In view of the fact that relays 300 `and 700 arestill operated on the return of the switches to normal, thesvvitcheswill repeat their vertical and rotary operati ons until the brushes 310or 710,1ind the mark-ed terminals 811 or 711 or until'the alarm circuitT functions to `restorethe connections to normal.

It should be noted that the operation of relay 514 also, by opening theconnection through its inner left-hand armature and back contact,removes theconimon battery from the position finder E. The operation ofrelay 514 also closes a circuit to ground for the operation of relay 528as follows: Battery, Winding ofrelay 528, inner right-hand armature andfront contact of relay 514 to ground. However before relay 528 has timeto operate a f 'circuit is completed through its malte-beforebreakcontacts for the operation of relay 410 as follows: Battery, Winding ofrelay 410, right-hand make-before-brealr contacts of this relay, outerright-hand armature and front contact of relay 405, brush and thecorresponding terminal of bank 536, malre-beforebreak contacts of relay528 to the ground at the inner right-hand armature and front Contact iof relay 514. Relay 410 in operating provides a locking circuit foritself through its righthand armature and front Contact to the ground atthe right-hand armature and front contact of` relay 406. While thisground from the inner right-hand armature and front Acontact of relay514 is removed from the terminal and brush of banlr 530 at themakebefore-break contact of relay 528 when it operates, a substituteground is provided for the A1brush ofrthis bank from the inner right-hand armature and back Contact of relay 537 through the left-handarmature and front contact of relay 538 and this ground is novv applied,due to the operation of relay 410, to another circuit as will behereinafter eX- plained. i

It should be noted that relay 410 in operating opens the circuit forrelay 407 extending through its left-hand makebefore-break contacts andtransfers this circuit through the outer left-hand armature and frontcontact to the ground connected at the inner righthand armature andbaclr contact of relay 537. '.llhus the control of relay 407 istransferred to the repeater Gr for supervisory purposes. It Will-benoted that there is another connection to ground from the left-handarmature of relay 52S into the repeater G through the armatures and backcontacts of the ringing relays 552 and 554. As relay 537 is operated,over a circuit which will hereinafter be traced, to insert a repeater ina connection by openmg its left-hand armature and back contact to removethe short-circuit across the repeater, the ground at the innerright-hand armature and baclr contact of relay 587 Will be removed.Hence the ground in the repeater will have control over the operationand release of relay 407. lf supervisory signals are incoming to therepeater G `from either line A or B to operate either of the ringingrelays 552 and 554 this above mentioned ground Will be removed to causethe release of relay 407. Relay 407 in releasing Will permit theoperation of relay 412 over an obvious circuit. Relay 412 in operatingWill close an obvious circuit for the operation of relay 413 which inturn closes a circuit for lighting of lamp 415. Hence the operationofrelay 528 transfers the supervisory control to the repeater from thecord circuit when the lines are connected through a repeater.

Another function performed by the operated relay 528is to close acircuit for the operation of relay 530 as follows: Battery, Winding ofrelay 530, make-before-break con tact of relay 529, right-hand armatureand front contact of relay 528 to the ground at the inner rightfhand ariat-ure and front contact of relay 514. Relay 530 in operating closes anobvious circuit for the operation of relay 531 Which in operating closesan obvious circuit for the operation of relay 529. Relay 529 inoperating opens the circuit for relay 530 and relay 530 opens thecircuit for relay 531. The relay 529 in operating closes a loclingcircuit through its right-hand armature and front contact to the groundat relay 514, so that this relay Will remain operated 'While relays 530and 531 are released. This sequence of operation Will take a certainperiod of time sufficient for the ringing currents from sources 228 and628 to burn out the brush and terminal contacts as hereinbeforedescribed. On the release of relay 531 a connection Will be completedfor the operaidc , A. It will nowvbe noted that the circuit from theground at relay 406 will extend through Vtion Ofielay 537Vover a circuitas follows:

' Battery; i rightihand :winding of' may left-hand armature, andifrontcontact of' relay 529,`right`h`and armaturel and back contact of relay531, a corresponding contact -andbrush ofbank 560, Yinner right-hand Yarmature'and front Contact of relay 405,

right-hand Varmature and back contact of relay 412, lower normal springsof ringing keys 430,' upper inner right-hand normal contacts oftalkingkey 401, right-hand arma- Y ture vand front contact'ofrelay 410, innerleft-hand armature'and front contact of relay 423, outer yright-handarmature and back Contact of relay 429, inner right-hand armature andfront contact of relay 406, to ground.

Relay 53'! in operatingl opens, at its left-hand and outer'right-handarmatures and back contacts, the usual short-circuiting bridge for therepeater G making it operative and places lamp-415 under the controlv ofrelays 552'and 554 ashereinbefore described. The same'circuit thatoperated relay' 537 also extendsj through relays 435, 226 and 626. Thecircuit for relay 435 is obvious and this relay in operating connectsthe monitoring leads fromrepe'ater G to the talking and monitoringkey401 so that if the operator desired to'monitor the connection she mayactuate this key towards the left and thus connect her telephone set tothe repeater. The circuit orrelay 226 may be traced as follows: Batltery, middle Winding of relay 226terminal then to the groundat relay406. Relay 226 in operating closes a locking circuit for itself throughits left-hand winding, 'armature andfront contactv to the'battery at theright-,hand armature 'and front `Contact of relay 22,1, and bytheoperation of this lethand'parmature the circuitgfor relay 224 isbroken to releasel this relay and'remove theringingfcurrent from theconductor of lineI y outerjar'mature and back contact of relay 224k thewinding of relay 230 through the upper so that Athis relay'230 willoperate and discon-4 neet the lineA from the'tip Vand ring terminal of jack 201 and connect it and a network N1 'through to the 'incoming endof'repeater `It seems unnecessary totrace the Vcircuit l romline Av andnetwork N1 to the incoming end of. repeater G as it is clear from thedrawing how this connection is completed.

On theoperation of relay 626 -a locking circuit is provided for thisrelay through its left-hand winding and left-hand armature and frontcontact through the armature and back contact of relay 632 to the groundat the outer right-hand armature and front contact of relay 618. It willbe noted that on the operation ,of relay 626 the circuit for relay 624is broken at the left-hand armature and back contact of this relay sothat relay 624is released and removes ringing current from theconductors of line B leading to the outgoing end of the repeater G. Whenrelay 624 releases the circuit from ground at relay 406 is extendedthrough the upper outer armature and back contact of this relay 624through the winding of relay 630 which now operates. This relay inoperating disconnects the line B from the tip and ring conductors ofjack 600 and extends it and the associated network N2 through the trunksclector I and the repeater finder K to the outgoing end of repeater G.As this connection from toll line B to the outgoing end of rcpeater G isalso clearly traceable on the drawing it seems unnecessary tospecifically describe it. A transmission connection is now thereforecompleted from line A to B that includes a repeater and conversationover this connection may now begin.

As the toll lines A and Bare now connected through the repeater G it isno longer necessary to prevent other cord circuits in other groups forestablishing connections. 1t will be noted that on the operation ofrelay 410, battery was connected at the inner lefthandarmature and frontcontact of this relay to the corresponding terminal and brush of bank501 and this has the effect of shunting the winding of relay 502 tocause the release of this relay. Relay 502 in releasing causes therelease of relay 510 which in turn causes the release of relay 503 andthe release of relays 502 and 503 causes the release of relay 512. Bythe release of relays 510 and 5,03 other cord circuits in this group orcord circuits in any other group that have been associated withcorresponding cord' finders, will be permitted to extend the connectionsthrough the relays corresponding to relays 510 and 503 of the positionfinder E. It should be understood that only one cord cir@ cuit at thetime will be permitted to complete a connection.

The time alarm circuit T operates as follows: On the operation of relay5.12 a circuit is provided for the operation of stepping magnet 540 asfollows: Battery, outer right-hand armature and back contact ofrelay541, armature and back; contact and winding of stepping magnet 540,outer left-hand armature and back contact of relay 541, inner right-handarmature and front contact of rery. en).

lay 512 to ground. l/Vhen the stepping magnet 540 operates to move thebrushes ot banks 542 `and 543 one step, the brush of bank 542 connectswith the first terminal which is connected to ground. rlhis causes acircuit to be closed for relay 541 as follows: Battery, outer righthandarmature and front contact ot relay 512, winding of relay 541,makebefore-break contacts of relay 541, winding of stepping magnet toground at the strapped terminals of bank 542. Relay 541 locks up t-oground at the inner right-hand armature and iront contact of relay 512through its inner right-hand armature and 'iront contact. Relay 541 inoperating opens the original energizing circuit for magnet 540 andprovides a circuit for the operation of relay 544 through interrupter545. Relay 544 in operating closes a secondary circuit for the operationof stepping magnet 540 as follows: Battery, outer right-hand armatureand trent contact of relay 541, armature and front contact oit relay544, winding of stepping magnet 540, brush ot bank 542 to ground. at thebank terminals. The interruptor 545 causes relay 544 to beintermittently operated to apply battery over its armature and frontcontact to the circuit for the stepping magnet 540. The stepping `magnet540 consequently is alterw nately operated and released to advance thebrushes of banks 542 and 543 step-byfstep under control of interrupter545. H this condition prevails for a certain period, for example, 5seconds, the brushes will have been advanced to a predeterminedposition. An alarm will then be given and the position finder and cord.tinder will be released to prevent holding up the system. It, :torexample, `'for some reason the system has failed to function in thisperiod the brush of the bank 543 will be advanced to terminal 546. Inthis position ground from the inner lett-hand armature and front contactof relay 541 will be connected through terminal 546, inner lefthandarmature and front contact of relay 512, the brush of bank 548 throughthe winding et relay 429 to battery. Relay 429 operates and locks undercontrol of the key 437 and causes the release of the position inder E asit places battery from its inner right-hand armature and front contacton the brush et bank 501 to release relay 502 and thus cause the releaseof relays 510, 503 and 512 in succession to release the position finderE as hcreinbetore described. rllhe operation of relay 429 also closes acircuit at its outer letthand armature and liront contact from batterythrough lamp 433 to ground through the winding of relay 434. Lamp 433lights and indicates to the operator that the circuit has failed tofunction properly and the operation ot relay 434 closes a circuit for analarm circuit 436 Which is common to the oiiice in which the tolloperator is located. The operation ol' key 437 restores the circuit tonormal condition. Assuming however, that the repeater is inserted in theconnection within the allotted time, the time alarm circuit will notfunction `to give an alarm due to the re lease of relay 512. Relay 512in releasing at the proper `time causes the release of relay 541 y whichcloses a` circuit from battery through stepping magnet 540 to ground onthe-terminals oit bank 542. The brushes of banks 542 and 543 are thusadvanced to the nekt position marked by terminals 546 or 547. Sincerelay 541 has been released the alarm circuitcannot be established inthese terminal positions. When the brush of bank 542 arrives at theterminals 549 or 550 no ground is iound on these terminals andcontequently the stepping magnet 540 will step withthe brushes in eitheroit these positions.

In case all ot the repeaters are busy battery through bank 513 of thecord iinder such as D, will not be available as all relays such as514,"will be actuated. However, battery through thewinding ot relay 551of the common meter circuit R will be available. The resistance ot theWinding oi: relay 551 will prevent relays, such as 431 and the steppingmagnet 51` from becoming operated but will allow the operation otrelay551 as `follows: Battery, winding of relay 551, outer righthand armatureand front contact ot a relay such as 503, outer lett-hand armature andback contact of a relay such as 512, armature and back Contact of arelay such as 515, a bank such as 520, Winding of a relay such as 431 toground. The operation of relay 551 causes the operation of a meter`magnet 553 over a circuit as follows: Battery, winding of meter magnet553, armature and front Contact oi' relay 551, through the contact 546or 547 of the time circuit when the brush 543 is advanced to this pointand to ground at the inner lett-hand armature and front contact of relay541. Thus the operation oit meter magnet 553 indicates the number oftimes repeaters were required and not available. It should be understoodthat it a repeater becomes idle betere the timing device operates thecircuit arrangement is such that this repeater will be selected in theymanner as hereinbei'ore described.`

Iii' the operator has occasion to actuate the talking key 401, afterrepeater' G has been connected with lines A and B relays 230, 630 and53'? `will be released. The release of relay 537 short-circuits thebridging points ot the repeater G and the release of relays 23() and630, disconnects lines A and B and the respective networks N1 and N2from the repeater G and connects them through the cord circuit and tothe operators telephone set.

In case supervisory signals come in while the repeater is insertedbetween lines A or B either the ringingrelay 552 or 554 is operated toremove the ground applied through the left-hand armature and trentcontact of l relay 528 to relay 407 which in releasing causes thelighting of lamp 415.

When vfor example, plug 400, is removed from toll line A thecircuitconnections will be restored to normal. That is, in line A relays 211and 21.2 release to cause the release of relays 215 and 207 which inturnl causes AVthe krelease' of relays 217, 221 and 226. In the cordcireuitthe release of. relays 404, 402 and 40.6causes the opening of thecemmon holding ground through the vinner right-hand armature and frontcontact of relay 406. Hence all the relays in the circuits that are heldoperated from this ground may be released. It should be noted that onthe release 'of relay 431, relay 300 of switch H is released to causelthe return of this switch to normal.

VOn the release of relay 300 a ground is connectedfat.itswright-handarmature Aand back cont-act for the operation ot release magnet 322. Onthe releaseof relay 307, relay 518 vis released thus causing the releaseof relay 514. The release of relay 514 causes the re-V lease ofrelays528 and 529. The release of relayl 5158 also causes therelease ofrelay 422 whichv in turn causes the operation of relay 610. Relayy610,,inoperating releases relay 615,. Relay. 6.15 causes the release ofrelay l618 and this relay causes the release of relay 633.. The releaseof relay 633 causes the release` of. relay 700 which permits theoperationofthe release magnet 722, which nowreturns switch K to normalposition.

vAlthough the present invention has been illustrated and describedparticularly in connection with toll systems it may be applied toswitchingisystems-not operated on the toll basis.

What is claimed ist:

1L In .atelephone system, lines, repeaters arranged for interconnectionbetween two ot said, lines, means Vfor designating said. two lines,means to designate ka repeater for selection, line selecting apparatusindividual to isaid repeaters, repeater selecting appa-V ratusindividual to' saidy lines, 'and means for actuating line select-ingapparatusfln response Vto the designation of a repeater and repeater theone end ot saidvrepeater to a line and for controlling the repeaterselecting apparatus ot another line to connect said other line to theother end of said repeater.

3. In a telephone system, lines, repeaters arranged tor interconnectionbetween two of said lines, cord circuits, line selecting apparatusindividual to said repeaters, repeater selecting apparatus individual tosaid lines, and means responsive to the connection of a cord circuitbetween two of said lines for controlling the line selecting apparatusof a. repeater to connect one end of said repeater te one ot said lines,and tor controlling the repeater .selecting apparatus of another line toconnect said other line to the other end of said repeater.

4. In a telephone system, lines, repeaters arranged for interconnectionbetween two of said lines, cord circuits, line selectors individual tosaid repeaters, repeater selectors individual to said lines, and meansresponsive to thc connection of one of said cord circuits between two ofsaid lines for controlling the line selecting apparatus ot a repeater toconnect one end ot said repeater to said first mentioned line and forcontrolling the repeater selecting apparatus of said second mentionedline to connect such line to the other end oit said repeater.

In a telephone system., lines, repeaters arranged tor interconnectionbetween two of said lines, line selecting apparatus comprising a linelindcr switch associated with one end ot each repeater for finding aline and connecting it with the corresponding repeater, rpeaterselecting apparatus comprising a trunk finder switch associated witheach line, a .plurality of trunks selectable by any one ot said trunkfinders and a repeater finder switch associated with each of said trunkshaving access to the other end of any one ot said repeaters, means forcontrolling the' line finder switch of a repeater to find one ot'saidlines and connect it to said repeater, and .means tor controlling thetrunk linder of anotherV line to iind an idle trunk and connect it tosaid other line and for controlling the' repeater finder associated withthe selected idle trunk te lind said repeater and connect said trunktherewith.

6. In a telephone system, groups of lines, groups ot' repeaters, meansto designate a repeater in a particular group tor selection, lineselecting apparatus associated with each repeater, the line selectingapparatus of each repeaterhaving access to a certain group of lines,repeater selecting apparatus individual to said lines and having accessto any one of the repeaters in any one of the groups, and means forcontrolling the line selecting apparatus ot' a designated repeater toselect a line in the assigned group and for controlling the repeaterselecting apparatus ot' any one rot the lines in any of they groups toselect connection to any line in any of the groups,

a group of repeaters assigned to each group ol cords, line selectingapparatus associated with each repeater, the line selecting appa-`paratus of the other line to connect said other line to said repeater.

8. In a telephone system, groups of lines, a group of cord circuits foreach group of lines arranged ler answering calls from the associatedgroup of lines and tor extending a connection to any line in any ot' thegroups, a group of repeaters assigned to each group of cords, lineselecting apparatus associated with each repeater, the line selectingappaiatus of the repeaters in each group having access to thecorresponding group ot lines, a group of repeater selecting appa-j ratusassigned to each group ot lines having accessto any one of the repeatersin any group, means responsive to the connection of a cord circuitbetween a calling line and another line for actuating the line selectingapparatus of a repeater assigned to the group of cords to which theconnected cord circuit belongs to connect said repeater with the callingline and for actuating the repeater selecting apparatus of the otherline to connect said other line to said repeater, and means responsiveto the connection oi' said repeater between said two lines for openingthe connection between said two lines established by said cord circuit.

9. In a telephone system, groups of lines, a group of cord circuits foreach group ot lines arranged for answering calls from the associatedgroup of lines and i'or extending connections to any of the lines in anyof the groups, a group of repeaters assigned to each group of cordcircuit-s, line selecting apparatus associated with each repeater, theline selecting apparatus of the repeaters in each group having access tothe lines answerable by a particular group of cord circuits, repeaterselecting apparatus comprising a trunk iinder for each line, trunks eachconnected at one end withstationary terminals of a plurality ot saidtrunk inders, repeater linder switches having movable brushes connectedto the other end of said trunks and stationary terminals connected tothe repeaters of all groups, all of said repeater finders thus having`gfaccess to any repeater in any group, means responsive to theconnection of a @0rd circuit between a calling line and another line forselecting an idle repeater in the group associated with the calling linefor actuating the corresponding line nder, -to find the calling line andconnect it to the selected repeater and means -tor acuating the tiniilrfinder et the other line to select an idle trunlr to actuate theassociated repeater iinder to iind the selected repeater and connect itto said other line,

10.` In a telephone system, incoming lines, outgoing lines, groups ofrepeaters, a line linder for each repeater for finding an incoming lineover which a call has been initiated, a repeater iinder for connectingan outgoing line to a repeater of any group, and

`means for actuating a line finder and a repeater `iiiider forinterconnecting an idle repeater between an incoming and an outgoingline.

ll. In a telephone system, incoming lines, outgoing lines, groups ofrepeaters, means to designate a repeater in one of said groups ior usebetween said lines, a line finder associated with the designatedrepeater for iinding the incoming line, a repeater iinder associatedwith the outgoing line for finding the designated repeater, and meansfor actuating said line finder and repeater finder thereby connectingsaid designated repeater bec tween said incoming and outgoing lines.

12. In a telephone system, incoming and outgoing lines, said linesvarying in transinission characteristics, automatically operable. meansto distinguish the character of an incoming` and an outgoing line todeterniine whether the addition of a repeater is required, lineselecting apparatus individual to said repeaters, repeater selectingapparatus individual to said lines, and means responsive to saiddistinguishing means for actuating the line selecting apparatus of arepeater and the repeater selecting apparatus of a line to interconnectsaid repeater between said incoming and outgoing lines.

13. In a telephone system, lines arranged for incoming or outgoingtelephone traino, repeaters arranged for interconnection between anincoming and an outgoing line, line selecting apparatus for saidrepeaters operable for selecting lines used for incoming traliic,repeater selecting apparatus for said lines operable when a line is usedfor outgoing traffic, and means for actuating the line selectingapparatus of a repeater and a repeater selecting apparatus of a line tointerconnect said repeater between an incoming and an outgoing line.

14. In a telephone system, lines, repeaters arranged for interconnectionbetween a line over which a call is initiated and a line to which saidcall is extended, line selecting apparatus :tor one end of saidrepeaters for selecting a line over which a call is initiated, repeaterselecting apparatus associated with

